Pinworms are common and might be returning guests. What you describe sounds like roundworms. The sudden itchy butt and the white specks, constipation etc. Please be aware that most cleaning products incl bleach do not work on worm eggs as they are mostly resistant to those. The only thing that helps is alcohol 96%, which i put in a spray bottle and wipe off with a paper towel. You should not become an obsessed clean freak as it is not needed. You can sensibly clean your place and toilet,.and wash your hands more often but ingesting the eggs is hard to avoid. They are in the air, on surfaces, especially on import food (yes, the global food chain is heavily contaminated), tap water, from pets etc. We can conclude that everyone has them except they might not have symptoms. You need to regularly parasite cleanse, use an ozonator to wash raw food products before eating, and be sensible. Buy local organic food if possible.
As soon as you feel the itch, do an enema. The butt can suddenly intensely itch when the worms are close to the anus. If i manage to do the enema right away i always manage to kill at least one. Full and new moon periods i even kill more. Roundworms need several meds at the same time, for at least a year. Besides meds you need to follow and intense detox and immune support protocol. Please see debugyourhealth.com for more tips.